1. Field of the Invention
The present invention is directed to a nozzle plate producing method, a nozzle plate, a liquid droplet ejecting head and a liquid droplet ejecting apparatus.
2. Description of the Prior Art
Ink jet heads (liquid droplet ejecting heads) are provided with a nozzle plate on which a plurality of minute nozzle holes are formed at a narrow spacing and is designed to perform printing operations by ejecting ink droplets from apertures (ink ejecting apertures) formed at one side of the nozzle holes and then landing the ink droplets on a printing paper. Reference is made to, for example, JP-A No. 2004-114415.
Some of such ink jet heads are of large size. In such ink jet heads, the size of a nozzle plate is also increased. The large-sized ink jet heads may be composed of a frame-like nozzle plate body and a plurality of small pieces (plate pieces) bonded to the nozzle plate body and having nozzle holes.
In producing the nozzle plate, first of all, a liquid-repellant coat composed of a fluorine-based resin or other like materials is formed on the ink ejecting aperture-side surface of each of the small pieces and on the inner circumferences of the nozzle holes at a region adjacent to each of the ink ejecting apertures. The reason for forming the liquid-repellant coat is that, once ink is adhered to the ink ejecting aperture-side surface of each of the small pieces, the flight trajectory of the ink droplets ejected next time becomes flexed under the influence of surface tension or viscosity of the ink thus adhered, which may cause the ink droplets to be landed on spots deviated from the targets. The liquid-repellant coat is formed to avoid such situation.
At the next step, the small pieces are bonded to the nozzle plate body. For this purpose, the liquid-repellant coat is removed from the bonding areas of the small pieces and then the coat-removed bonding areas of the small pieces are adhesively bonded to the nozzle plate body.
One known example of the method for removing the liquid-repellant coat is a photolithographic method. With this method, however, a large number of steps must be carried out for removal of the liquid-repellant coat, thus making the overall process complicated. This leads to increased costs in producing the nozzle plate.